Some smartphones and tablet PCs each with a display include, on a display screen, a protective plate such as a glass plate or a transparent plastic plate. Here, optical bonding for bonding the protective plate with, for example, an adhesive made of a transparent resin may be adopted to improve its design and display characteristics.
The displays include, for example, a liquid-crystal display panel. The liquid-crystal display panel contains liquid crystals between a thin-film transistor (hereinafter referred to as “TFT”) substrate and a counter substrate that is disposed to face the TFT substrate. The TFT substrate is obtained by forming TFTs that are switching elements. Recent liquid-crystal display panels have adopted an in-plane switching mode or a fringe-field switching mode with wide viewing angle characteristics. In the in-plane switching mode or the fringe-field switching mode, an electric field generated in a transverse or diagonal direction allows liquid crystals to move in a plane of a substrate with an array of TFTs. Since electrodes that drive the liquid crystals are collectively formed on the TFT substrate in these modes, the counter substrate does not need any electrode for driving the liquid crystals.
However, application of electrical noise such as static electricity to a surface of the counter substrate that is not in contact with the liquid crystals in the in-plane switching mode or the fringe-field switching mode creates a problem of causing the liquid crystals to respond to the noise and thus displaying an irregular image. To address this problem, a structure of dissipating electric charges has been used by forming a transparent electrode made of, for example, a transparent substance (for example, indium tin oxide hereinafter referred to as “ITO”) on a surface of a counter substrate that is not in contact with liquid crystals and connecting the transparent electrode to GND of the system.
Patent Document 1 describes, as a conventional method, a structure of connecting a transparent electrode disposed on a counter substrate to a conductor and GND of a circuit board. In a display described in Patent Document 1, a transparent conductive film is formed on the surface of a transparent cover glass, and a liquid-crystal display panel is housed in a casing. Ground connection of the transparent conductive film through a conductive film formed in the casing creates a structure of dissipating electric charges accumulated in the transparent cover glass toward the casing.
Patent Document 2 describes a structure of connecting a transparent electrode of a counter substrate to a ground line provided on a TFT substrate via a conductive paste. In a display of Patent Document 2, a structure of forming a transparent conductive layer on the rear surface of a transparent plate disposed on the top surface of the counter substrate to shield a pair of the substrates by the transparent conductive layer is disclosed, which allows static electricity to flow from the transparent conductive layer toward the ground of a circuit board through a conductor and a metal line without the static electricity being accumulated in liquid crystal cells.